Enhanced organically bound selenium yeast production by fed-batch fermentation

This study describes a fed-batch fermentation protocol for enhanced production of Saccharomyces cerevisiae containing organically bound selenium. Two levels of sodium selenate concentrations were applied as either a single dose or continuous addition. Fermentations with high sodium selenate (63.2 g/L in cane molasses feeding medium) demonstrated 24 g/L of biomass with 1382 microg of selenium/g of dry biomass for single-dose addition and 40 g/L of biomass with 1491 microg of selenium/g of dry biomass for continuous addition. Low selenium concentration (31.6 g/L in cane molasses feeding medium) demonstrated higher biomass concentration with higher selenium level; 37 g/L of biomass with 2846 microg of selenium/g of dry biomass and 45 g/L of biomass with 2495 microg of selenium/g of dry biomass for single-dose and continuous addition, respectively. Also, two adapted S. cerevisiae strains were evaluated in fed-batch fermentation. A single dose of low concentration demonstrated >3000 microg of selenium/g of dry biomass, but biomass concentration was lower (< or =32 g/L) for these adapted strains.     

Enhanced organically bound chromium yeast production

This paper describes continuous and fed-batch fermentation protocols for enhanced production of organically bound chromium yeast. During continuous fermentation, several inorganic chromium compounds were evaluated. Sodium chromate demonstrated the best chromium incorporation into yeast biomass without any precipitation in the fermentation medium. During fed-batch fermentation, several sodium chromate concentrations were evaluated at 1.1, 3.5, 5.9, 7.1, 8.3, and 10.8 g/L with continuous or single-dose addition. For single-dose addition of sodium chromate, some precipitation was observed for all concentrations, which reduced the available chromium in the fermentation medium. Adapted strain C11-1, obtained during continuous fermentation, produced higher biomass than the wild type but significantly lowered chromium incorporation. Pilot-scale fermentation demonstrated similar total chromium incorporation (2966 ppm) with lower biomass production compared to benchtop fermentation performed at the same sodium chromate addition.     

Hydrochemical modelling of a stream dominated by organic acids and organically bound aluminium

An existing hydrogeochemical model, the Birkenes model (BIM), has been extended to include production of dissolved organic carbon (DOC) in the soil/water system and its chemical interactions with H⁺ and A1³⁺. The model has been calibrated and verified using precipitation and runoff data from the Svartberget catchment in northern Sweden. The catchment is impacted by moderate amounts of sulphur deposition (6 kg S ha^?1 a^?1; the stream is high in DOC (7–35 mg L^?1) and experiences episodically low pH-values (～4.0). The refined BIM is able to simulate the main variations in major chemical components of the stream water (H⁺, Ca²⁺, Mg²⁺, Al_i, Al₀, Cl^?, SO₄ ^?2 and DOC), as well as stream discharge and ¹⁸O, while Na⁺ is not well reproduced. Although very simplified relationships are used for the chemical interactions between DOC and H⁺ and aluminium, the model shows that these interactions are essential to stream acidity and aluminiumspecies content. Some of the model parameters are poorly determined by calibration with runoff data only. Soil and soil water investigations may contribute to the evaluation and development of the model structure and the representation of chemical processes. Further improvements of the model should emphasize DOC-production/absorption, detailed studies on DOC chemical behaviour and hydrological structure.     

Hydrolysis and transformation of grape glycosidically bound volatile compounds during fermentation with three Saccharomyces yeast strains

The ability of three Saccharomyces wine yeasts (S. cerevisiae AWRI 838, S. cerevisiae AWRI 1537, and S. bayanus AWRI 1375) to liberate volatile compounds from sugar-bound aroma precursors was investigated using synthetic and grape glycosides under different experimental conditions. In model systems involving the incubation of yeast cells with either synthetic or grape-derived glycosides under conditions more favorable for glycosidase activities and less favorable for acid-catalyzed hydrolysis (pH 5.0 and 30 degrees C), all yeast strains studied proved to be capable of hydrolyzing glycosides, with S. bayanus AWRI 1375 displaying greater hydrolytic activity than S. cerevisiae AWRI 838 and AWRI 1537. During the fermentation of a chemically defined grape juice-like medium containing glycosidic precursors extracted from Vitis vinifera cv. White Frontignac (synonym Muscat à Petit Grains Blanc), all yeasts promoted a significant hydrolysis of different precursors, which varied according to the chemical structures of both the sugar and the aglycon moieties, as determined by GC-MS analysis of trifluoroacetylated derivatives. Hydrolysis of the White Frontignac derived glycosidic precursors during fermentation resulted in the release of monoterepene alcohols, terpene oxides, terpene diols, and 3-oxo-alpha-ionol, demonstrating the significant potential of these yeast strains to contribute to wine varietal volatile composition during alcoholic fermentation.     

Net change in organically bound halogens in relation to soil pH

The total amount of organically bound halogens was determined in soil samples from the Palace Leas meadow hay plots, Northumberland, UK. These plots have been amended with different combinations of farmyard manure, potassium chloride, ammonium sulphate or nitrate since their establishment in 1897, resulting in, among other things, substantial pH differences between the plots. It was found that the amount of organically bound halogens increased significantly with decreasing pH. Net changes in amounts of organohalogens were also studied in soil obtained from a coniferous forest in southern Sweden. The collected soil was divided into four sets of samples, which were incubated in a climate chamber and subjected to different treatment regimes that influence soil pH. Significant changes in amounts of organically bound halogens were detected in three of the four sets of samples, resulting in significantly increasing amounts with decreasing pH. However, although the amount of organically bound halogens detected was related to soil pH in both the field and the experimental study, the net changes observed in the latter investigation were not directly related to soil pH. This shows that net changes in the amount of organically bound halogens in soil are caused by complex processes, and that further studies are needed to clarify the nature of the observed relation between soil pH and amounts of organically bound halogens.     

甜高粱茎秆汁液固定化酵母酒精发酵的研究

本文应用一元线性回归分析法得出了甜高粱茎秆汁液锤度和可溶性总糖含量之间的关系。以甜高粱茎秆汁液为原料,在摇床及流化床反应器上进行了固定化酵母酒精发酵的试验研究。结果表明,以沈农甜杂2号甜高粱为原料,在摇床上作营养盐配比的正交试验,试验得出对提高酒精得率影响因素的主次顺序为：(NH₄)₂SO₄,K₂HPO₄,MgSO₄。最优组合为：0.125% K₂HPO₄,0.200%(NH₄)₂SO₄,0.050% MgSO₄。加营养盐的酒精得率比不加任何营养盐的酒精得率可提高4.0%～8.0%。K₂HPO₄,(NH₄)₂SO₄的配比对试验结果影响极显著,MgSO₄的配比对试验结果影响显著。在流化床反应器上试验,4种较优营养盐组合酒精得率近乎相等,比不加营养盐空白试验酒精得率高。从降低成本角度来讲,选择0.125% K₂HPO₄,0.200%(NH₄)₂SO₄,0.010% MgSO₄作为投产试验。本文为燃料乙醇的发展提供了科学的依据。     

Enzyme additions as a tool to assess the potential bioavailability of organically bound nutrients

Potential enzyme activities in soil and water samples are measured by addition of an excess amount of suitable substrate and subsequent determination of product release. If the approach is reversed and an excess of enzyme is added, substrate availability becomes rate-limiting and the maximum release of product indicates the availability of a given substrate in a sample. This approach has been used in a range of studies using phosphatase enzyme additions to soil, manure and sediment extracts, soil suspensions, and lake and sea water (n = 41). Significantly fewer studies have used enzymes from the carbon, nitrogen and sulfur cycles (n = 14). In this review, the methodological aspects of enzyme additions are discussed using examples from studies in which enzymes from the phosphorus cycle were used. A meta-analysis performed for various soil extracts and water samples revealed that the majority of studies (75th percentile) indicate availability of organic phosphorus to enzymatic hydrolysis of up to 60%, with crude phytase preparations showing the lowest substrate specificity and greatest release of phosphorus. Compared to addition of enzymes from the phosphorus cycle, lower substrate degradation was generally achieved by addition of enzymes from the carbon, nitrogen and sulfur cycles to soil suspensions and soil organic matter extracts. Enzyme additions can be a valuable tool in process research, provided all the necessary controls are included and assay conditions optimized to ensure that the reaction reaches completion. Recommendations for the development of a standard protocol are made.     

Adsorption of anthocyanins by yeast cell walls during the fermentation of red wines

This paper reports the anthocyanin adsorption profiles of the cell walls of different Saccharomyces strains isolated from grapes collected in the Spanish appellation controlée regions of La Rioja, Navarra, and Ribera del Duero. These strains are habitually used in red wine-making. The acyl derivatives of anthocyanins (acetyl and p-coumaryl compounds) were more strongly adsorbed than nonacyl derivatives. Peonidin-3G was also strongly adsorbed, as were its acyl derivatives. The greater presence of acetyl derivatives in the cell wall adsorbate leads to an increase in yellow color and a reduction in blue color with respect to the corresponding wine.     

Low-temperature alcoholic fermentation by delignified cellulosic material supported cells of kefir yeast.

A novel system for low-temperature alcoholic fermentation of glucose is described. This system consists of kefir yeast immobilized on delignified cellulosic materials. Batch fermentations were carried out at various pH values, and the effect of temperature on kinetic parameters, in the range of 5-30 degrees C, was examined. At pH 4.7 the shortest fermentation time was obtained. The formation of volatiles indicates that the concentration of amyl alcohols (total content of 2-methylbutanol-1 and 3-methylbutanol-1) is reduced as the temperature becomes lower. Propanol-1 and isobutyl alcohol formation drops significantly below 15 degrees C. The percentage of ethyl acetate increases as the temperature is diminished. At 5 degrees C the content of total volatiles in the product was only 38% of the volatiles formed during fermentation at 30 degrees C.     

甜高粱茎秆固态发酵生产燃料乙醇研究

该文通过研究甜高粱茎秆M-81E固态发酵生产燃料乙醇的主要影响因素,确定发酵条件为:耐高温酿酒酵母接种量为3%,发酵初始基质含水率为76%,添加0.25?Cl2,0.25%MgS04·7H2O,40℃发酵24 h,乙醇得率为6.42 g/(100g)甜高粱茎秆,转化率为90.5%,残糖含量低于0.3%;添加10 FPU/g纤维素酶和10 CBU/g β-葡萄糖苷酶,进行同步糖化固态发酵,乙醇得率为7.53 g/(100 g)甜高粱茎秆,与不添加纤维素酶和β-葡萄糖苷酶的相比,乙醇得率提高了14.6%.     

Relationship between the decreases in soil stability effected by the growth of maize roots and changes in organically bound iron and aluminium

The growth of maize roots decreased fresh soil aggregate stability. Chemical pretreatment with sodium periodate (to assess the importance of polysaccharides) and acetylacetone (to assess the importance of organically bound Fe and Al) before measuring stability suggested that destruction of (organic matter)-(Fe or Al)-(mineral particle) linkages largely accounts for the effect. Removal of the Fe and Al cations by chelating agents released in the rhizosphere is the most likely mechanism. Changes in soil particle size distribution and the concentrations of water-extractable cations around maize roots did not appear to be implicated. Concentrations of water-extractable Mg and K were sometimes greater in fresh soil which had supported maize than in fallow controls, which may reflect both release of bicarbonate or organic anions by the roots and the slaking of aggregates, reducing stability of the fresh maize soils.     

Effect of carbohydrate substrate on fermentation by kefir yeast supported on delignified cellulosic materials

The suitability of delignified cellulosic (DC) material supported kefir yeast to ferment raw materials that contain various single carbohydrates, for the production of potable alcohol and alcoholic drinks, is examined in this investigation. Results are reported of fermentations carried out with sucrose, fructose, and glucose in synthetic media. Repeated batch fermentations at various initial sugar concentrations of sucrose, fructose, and glucose were performed at 30 degrees C in the presence of the aforementioned biocatalyst. The results clearly show feasible yields in the range of 0.38-0.41 g/g, alcohol concentrations of 7.6-8.2% v/v, fermentation time of 90-115 h, and conversion of 92-96%. DC material supported kefir fermented 11-fold more rapidly than free cells and 9-fold more rapidly in comparison to kissiris supported kefir. The main volatile byproducts such as amyl alcohols (mixture of 2-methyl-1-butanol and 3-methyl-1-butanol), ethanal, and ethyl acetate were formed in all sugar fermentation products. The formation of 65-110 ppm of ethyl acetate is as high and even higher than that obtained with traditional wine yeasts. The increase of the initial concentration of sugar in the fermentation media resulted in an increase in contents of volatiles. The fine aroma that was obtained in the product of fructose could be attributed to the high percentage of ethyl acetate on total volatiles. The efficiency of DC material supported kefir was the same for the fermentations of individual sugars or a mixture of fructose, sucrose, and glucose. When whey with raisin extracts was fermented, lower yields were obtained but the aroma of the product was even better.     

利用甜高粱秸秆汁发酵生产丁醇、丙酮

该试验以甜高粱秸秆汁作为生产丙酮、丁醇的发酵原料,从5种丙酮-丁醇菌中选出能够利用甜高粱秸秆汁且丁醇产量高的Bacillus acetobutylicum Bd3菌作为试验菌株,并对该菌株的发酵条件进行优化,得到的优化条件为:糖度为10oBrix的甜高粱秸秆汁,玉米浆含量5 g/L,接种量6%(v/v),(NH4)2SO4 5 g/L,KH2PO4 0.4 g/L,CaCO3 6 g/L,温度32℃,pH6.8,丁醇产量达到10.29 g/L。     

以菊芋粉为原料同步糖化发酵生产燃料乙醇

利用粟酒裂殖酵母（Schizosaccharomyces pombe）能发酵菊芋未水解糖液高产乙醇的特点提出了以菊芋粉为原料,同步糖化发酵生产燃料乙醇的新工艺。在摇瓶中考察了原料预处理方法、原料浓度和初始pH值对乙醇发酵的影响,进而在5 L发酵罐中考察了未调控pH值和恒定pH值与通气情况对乙醇发酵的影响。结果表明：该菌株最适pH值为4.0;100目筛分的菊芋粉发酵效果良好,115℃灭菌处理优于121℃,在此条件下,菊芋粉浓度200 g/L时,乙醇产量达到66.58 g/L,理论转化率为85.88%;发酵液pH值下降对乙醇发酵没有影响,通入适量氧气会导致乙醇产量的下降,这表明粟酒裂殖酵母进行乙醇发酵时不需要供氧;通入氮气保持厌氧环境不能显著提高乙醇产量,不通气进行乙醇发酵也达到高的转化率,因此在工业生产中,不必保持厌氧发酵环境。在此基础上,对菊芋粉补料发酵进行了试验,补料至菊芋粉终浓度为300 g/L,发酵终点乙醇浓度为94.81 g/L,理论转化率为81.54%。这些研究工作,为以菊芋为原料的燃料乙醇工业化生产提供技术依据。     

批式与连续两相发酵的果蔬废弃物厌氧产气性能

该研究采用批式试验与连续发酵试验探讨了苹果与蔬菜废物的厌氧发酵产气性能,结果表明:38℃下苹果与蔬菜废物混合进行厌氧发酵发生了协同促进作用,显著提高了混合原料的产气能力。在苹果废物与蔬菜废物的混合比例F:V=4:1时,混合原料的产沼气潜力达到了914.6 L/kg。利用修正的Gompertz模型能够很好的模拟果蔬废物批式厌氧发酵产气的累积产气过程,拟合结果的R2在0.983~0.999之间。果蔬废物连续进出料产气过程研究结果表明在HRT=24 d、35℃中温发酵条件下,果蔬废物为原料的一体化两相(combined two phase,CTP)反应器有机负荷OLR可达2.5 g/(L·d)时,此时CTP反应器的产气量最高可达12.9 L/d,反应器内物料比产气量为390 L/kg。这表明CTP反应器可以作为果蔬厌氧发酵产气的反应器。与全混式反应器相比,CTP反应器结构简单、成本低,但对果蔬废物的发酵效率低于全混式反应器。     

Comparison of biotransformation of inorganic selenium by Lactobacillus and Saccharomyces in lactic fermentation process of yogurt and kefir

The aim of the present study was to characterize, quantify, and compare the different selenium species that are produced when lactic fermentation with two different types of microorganisms, bacteria (Lactobacillus) and yeast (Saccharomyces), take place to produce yogurt and kefir, respectively, and to study the transformation process of these species as a function of time. These two dairy products were chosen for the study because they are highly consumed in different cultures. Moreover, the microorganisms present in the fermentation processes are different. While the bacteria Lactobacillus is the one responsible for yogurt fermentation, a partnership between bacteria and the yeast Saccharomyces causes kefir fermentation. A comparative study has been carried out by fermenting Se(IV) enriched milk in the presence of both types of microorganisms, where the concentration range studied was from 0.5 to 20 microg g (-1). Enzymatic extraction enabled selenium speciation profiles, obtained by anionic exchange and ion-pairing reversed phase high performance liquid chromatography (IP-RP-HPLC) with inductively coupled plasma mass spectrometry (ICP-MS) detection. Scanning electron microscopy (SEM) applied to the enriched samples showed segregated Se (0), at added concentrations higher than 5 microg g (-1). The main Se species formed depended on the type of microorganism involved in the fermentation process, SeCys 2 and MeSeCys being the main species generated in yogurt and SeMet in kefir. The results obtained are different for both kinds of samples. Lactic fermentation for yogurt produced an increment in selenocystine (SeCys 2) and Se-methylselenocysteine (MeSeCys), while fermentation to produce kefir also incremented the selenomethionine (SeMet) concentration. The Se species are stable for at least 10 and 15 days for kefir and yogurt, respectively. After this period, selenocystine concentration decreased, and the concentration of Se-methylselenocysteine was found to significantly increase.     

Identification of organically bound iodine in soil humic substances by size exclusion chromatography / inductively coupled plasma mass spectrometry (SEC / ICP-MS)

Abstract

Sulfur transformation in riee rhizosphere was investigated. Soil enzyme arylsulfatase in rhizosphere and non-rhizosphere soil, whieh is responsible for mineralization of organic sulfur to sulfate sulfur, was studied. The Michaelis constants of arylsulfatase from Maahas c1ay and Pila c1ay loam were 3.04 × 10^-4 M and 3.97 × 10^-4 M, respectively. The arylsulfatase of rhizosphere soil showed higher activity than that of non-rhizosphere soil. Applieation of sulfate had no marked elTect on the enzyme aetivity either in rhizosphere or non-rhizosphere soil under the submerged condition. This indieates that arylsulfatase activity under the submerged condition is not inhibited by applieation of sulfate. The amount of HI-reducible sulfur in the rhizosphere and non-rhizosphere soi! inereased with time. However, rhizosphere soil had a higher amount of HI-reducible sulfur than did non-rhizosphere. Thc ditl'erence in arylsulfatase activity between the rhizosphcre and non-rhizosphere soil was not directly associated with thc number of sulfur-redueing and -oxidizing bacteria.     

蛋氨酸硒对西门塔尔牛瘤胃发酵及尿嘌呤衍生物的影响

选用4头平均体重420 kg、年龄2.5岁装有永久性瘤胃瘘管的西门塔尔牛阉牛,采用4x4拉丁方设计,以混合精料和风干玉米秸秆为基础日粮,以蛋氨酸硒为硒源,在基础日粮中分别添加硒0 mg·kg-1、0.3mg·kg-1、0.6 mg·kg-1和0.9 mg·kg-1,研究蛋氨酸硒对西门塔尔牛瘤胃pH、氨态氮、VFA、营养物质降解率及尿嘌呤衍生物浓度的影响.结果表明:不同浓度硒处理间西门塔尔牛瘤胃pH、挥发性脂肪酸(VFA)和乙酸,丙酸无显著差异(P>0.05),氨态氮浓度显著低于对照(P<0.05);0.6mg·kg-1硒处理组西门塔尔牛玉米秸秆干物质(DM)、有机物质(OM)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)和豆粕DM、OM、粗蛋白质(CP)有效降解率均显著高于对照(P<0.05);0.6mg·kg-1和0.9mg·kg-1硒处理组西门塔尔牛尿囊素和尿嘌呤衍生物浓度显著高于0.3 mg·kg-1组和对照组(P<0.05);西门塔尔牛日粮以蛋氨酸硒为硒源时,硒的适宜添加浓度为0.6 mg·kg-1.     

酵母菌PA4酿造苹果酒发酵条件的优化

通过三因素二次正交旋转回归实验设计，考察了发酵温度、接种量、发酵液初始pH值对酵母菌PA4酿造苹果酒品质的影响，得出苹果酒质量与影响因素的回归模型。结果表明：发酵温度和接种量对苹果酒质量的影响极显著(p＜0.01)，发酵液初始pH值对苹果酒质量的影响显著(p＜0.05)；菌株PA4酿造苹果酒的最佳工艺参数是发酵温度为24℃，接种量为10%，pH值为3.4。     

Stability of patulin to sulfur dioxide and to yeast fermentation.

The affinity of patulin for sulfur dioxide (SO2) is much less than was previously reported and is of little significance at the SO2 concentrations (below 200 ppm) used in the processing of apple juice and cider. However, at concentrations of 2000 ppm SO2 and 15 ppm patulin, combination was 90% complete in 2 days. Removal of SO2 liberated only part of the patulin, which suggests that 2 mechanisms are involved: one reversible (opening the hemiacetal ring) and one irreversible (SO2 addition at the double bond). Test with 2 yeasts used in English commercial cider making confirmed that patulin is effectively removed during yeast fermentation.